Heated fuser roll



April 8, 1969 A. T. MANGHIRMALANI ETAL 3,437,032

HEATED FUSER ROLL Filed July l, 1965 v .l Sheet of 2 BY nf/Av A from/5 rs April 8, 1969 A. T. MANGHIRMALANl ETAL 3,437,032

HEATED FUSER ROLL Filed July 1, 1965 sheet 2 of 2 /NVE/VTOHS ARJAN T. MANGHIRMALANI ANDREW F. TRABOLD ROBERT H. FIGLER ATTORNEYS United States Patent O1 U.S. Cl. 100--93 2 Claims ABSTRACT F THE DISCLOSURE Apparatus for transferring heat energy and pressure energy to an image bearing support material to effect fixing of said image.

This invention relates to an improved heated roller.

More specifically, the invention relates to an improved roller for use in a xerographic fusing device of the type disclosed in Copending application Ser. No. 400,498, filed Sept. 29, 1964, in the names of Gilbert A. Aser, Robert H. Figler and Thomas P. Redding, now Patent No. 3,291,- 466 which issued Dec. 13, 1966 or a similar device. Although the invention is considered to have general application, it is particularly use-ful in the lield of xerography and has an important application in the heated pressure fusing ydevice used in fusing resinous powder images produced by electrophotography or xerography onto sheets of paper and the like to which the powder images have been transferred after they have been formed by deposition of powder on an electrostatic latent image, as disclosed in said Copending application.

One of the methods in common use for developing the electrostatic latent image is described in Walkup Patent No. 2,618,55'1, and is known as casca-de development, and is in general use for line copy development. In this technique, the powder or toner is mixed with a granular carrier material, and this two-component developer is poured or cascaded over the plate surface. The function of the carrier material is to improve the flow characteristics of the toner and to produce, on the toner, by triboelectrification, the proper electrical charge so that the toner will be attracted to the image. More exactly, the function of the carrier material is to provide ,the mechanical control of the toner or to carry the toner to an image surface and, simultaneously, the provide homogeneity of charge polarity.

In Carlson Patent 2,297,691, it is noted that a variety of types of finely divided electroscopic powders may be employed for developing electrostatic latent images. However, as the science of xerography has progressed, it has been found preferable to develop line copy images with a powder or toner formed of any of a variety of pigmented thermoplastic resins that have been specifically ldeveloped for the purpose. A number of such developing materials are maniufactured and marketed commercially and are specifically compounded for producing dense images of high resolution and to have characteristics to permit convenient storage and handling. Such developing materials are compounded to permit them to be fixed to the surface of a transfer material either by heat `fixing or vapor fixing techniques, in accordance with the particular application in which they are employed, that is, the individual particles of resin (toner) soften and coalesce when heated or plasticized by solvent, so that they become sticky or tackitied and readily adhere to the surface of the support material.

The term tackified and the several variant forms thereof used throughout this specification are employed to define the condition of the powder particles of the xerographic powder image when heated or plasticized by hee a Solvent in a manner such that the individual particles soften and coalesce and in which state they become sticky and readily adhere to other surfaces, Although this condition necessarily requires a flowing together of the particles to effect a thorough fusion thereof, it is to be understood that the extent of such flowing is not sufficient to extend beyond the boundary of the pattern in which the particles are formed.

One of the important applications of the process of xerography comprises its use in automatic copying machines for general oflice use wherein the powder images formed on a xerographic plate are transferred to paper and then fixed thereon by heat fusing. In order to fuse resinous powder images formed of the powdered resins now commonly used, it is necessary to heat the powder and the paper to which it is to be fused to a relatively high temperature, such as approximately 325 F. It is undesirable, however, to raise the temperature of the paper substantially higher than 375 F. for long periods of time because of the tendency of paper to discolor at such elevated temperatures.

It has long been recognized that one of the fastest and most positive methods of applying heat for fusing the powder image to paper is to bring the powder image into direct contact with a hot surface, such as a heated flat plate.

But, as the powder image is tackii'ied by heat, part of the image carried by the support material will stick to the surface of the heated plate so that as the next sheet is placed on the heated plate, the tackified image partially removed from the -flrst sheet will partly transfer to the next sheet and at the same timt part of the tackilied image from said next sheet would adhere to the heated plate. This process is commonly referred to in the printing art as set off or offset, the latter term being preferred.

The offset of toner onto the heated contacting surface has heretofore led to the rejection of contact fusers in favor of other heat fixing devices, primarily coiled radiant element heaters with reflectors. These radiant element heaters with reflectors have the disadvantage of dissipating a large quantity of heat into the machine enclosure in which they are used, heat transfer by radiation to the powder image is inefficient, and they present a safety hazard because of the expostd radiant element.

Copending application Ser. No. 440,498, provides a direct contact fusing device which will rapidly fuse toner images |without causing the toner particles to smear while in a tackied state or to offset onto the device. A roller manufactured in accordance with the disclosure of this application may be used, for example, in such a fuser and, therefore, for convenience of illustration, the invention is described with reference to its use in this type heat fuser. However, it is to be understood that it may be employed with equal facility in other fields.

A roller used in such a fuser must have suitable thermal conductivity to assure proper fusing and be resistant to toner olfset to prevent the tackilied image on the support material from adhering to the roll and being deposited on the subsequently passing sheets of support material.

Teflon TFE, a trademark of DuPont Corporation for a product of tetralluoroethylene resin, is a suitable product for use on a roller to be used in such a fuser. It has been found that the use of copper rollers for a heated roller is highly desirable owing to the thermal conductive characteristics of this material. However, Teflon does not adhere t'o copper; and, therefore, before the development of the process claimed in this application, Teflon could not be bonded to copper rollers suiliciently for use in a heated pressure fuser.

It is thought that the reason that Teflon-copper bond is not suitable resulted from the formation of loose cupric oxide on the copper roller at temperatures necessary for the fusing of the Tefion enamel spray coating. Experimentation with the T eflon-copper bonding resulted in suitable bonds when nickel was plated onto the copper roll prior to the spray coating of the Tefion. It is thought that this plating prevented the formation of loose cupric oxide. Ebanol C, a tradename for a copper blackening material available from Enthone, Inc., a subsidiary of American Smelting & Refining Company, was used to treat the copper rolls prior to the Teflon application and produced a sufficient bonding. It is thought that Ebanol C produces a thin, tightly adhering cupric oxide film which prevents further oxidation resulting in the formation of undesired loose cupric oxide. While the Ebanol C treatment produces a satisfactory Tefion-copper bond, the use of the nickel plating is preferred.

It is, therefore, the object of this invention to manufacture heated rollers suitable for use in a heated pressure fusing device.

It is a further object of this invention to improve the construction of a heated roller to attain efliceint heat transfer to the toner image to be fused.

Another object of this invention is to improve the process for manufacturing heated contact rollers having suitable thermal conductivity, resistance to silicone fiuid, ozone and toner resistance, and having suitable triboelectric properties.

These and other objects of the invention are attained by means of a roller including a copper cylindrical core to which a coating of an abhesive material such as Teflon TFE is secured by a suitable process.

Abhesivef is a relatively new term that was coined by Dow Corning Corporation primarily in connection with their silicones to define a surface that has release characteristics such that it is highly repellant to sticky or tacky substances.

For a better understanding of the invention, as well as other objects and further features thereof, reference is had to the following detailed description of the invention to be read in connection with the acompanying drawings, wherein:

PIG. 1 illustrates a preferred embodiment of a roller manufactured in accordance with this disclosure being used in a heated pressure fusing device;

FIG. 2 illustrates a roller being constructed in accordance with the disclosure;

FIG. 3 is a top section view of a roller constructed in accordance with this invention to more clearly illustrate the parts.

Referring now to FIG. 1, there is shown a heat fuser device including an upper roll 1 suitably journaled in vertical frame plates 3 and 4 secured in spaced relation to a base 5. The upper roll is provided internally with a heating element 8.

To effect fusing of a toner image on a support material, the support material is brought image-side up into the pressure contact with the upper roll 1, constructed in accordance with the invention, by advancing the support material between the upper roll 1 and a bottom pressure roll 2.

To prevent toner offset onto the upper roll 1, its peripheral surface is covered with a coating of an adhesive material, such as Teflon TFE. In addition, a thin film of an abhesive liquid, such as a silicone iiuid, is applied to the surface of the upper roll 1.

For further details of the heat fuser shown in FIG. l, reference is made to the above-referenced Aser et al. application Ser. No. 400,498.

Referring now to the subject matter of the invention, the heat roll 1 includes a cylinder 10 partly closed at opposite ends by left-hand and right-hand fuser roll caps 11 and 12, respectively, which are secured to the cylinder, as by brazing. The roll is journaled for rotation by bearings 13 and 14 positioned in frame plates 3 and 4,

, respectively.

The inner race of bearing 13 is secured to cap 11 by a set screw 15. Thrust washer 16, which encircles the spindle portion of fuser roll cap 11 between the bearing 13 and a retaining ring 17, secured in a suitable groove provided in frame plate 3, retains the outer race of this bearing while allowing for expansion of heated roller 1 when in operation.

On the opposite end of the roller, the inner race of bearing 14 is secured to the hub portion of sprocket hub 18. Sprocket hub 18 encircles the spindle portion of cap 12, and is connected for rotation therewith upon engagement of tab 19 on the sprocket hub with a suitable notch provided in the cap 12. The outer race of bearing 14 is retained in position in frame plate 4 by retaining ring 21 secured in a suitable annular groove in the frame plate.

Each of the fuser roll caps is provided with a suitable aperture to receive a quartz tube 7 which supports a suitable resistance heating element 8. Resistance element 8, which extends through roll 1, is connected by suitable conductors 22 :to a source of power, the outboard conductor being covered by cap 23. A thermostat 24, part of an electrical control system for controlling power to the resistance element 8, is suitably positioned in thermal relation with an uncoated portion 25 of fuser roll 1.

To prevent toner offset onto the heated roll contacting the unfused toner image on the support material, an olfset preventing material 9 covers the outer surface of cylinder 10 of roll 1. A suitable material is a coating of Teiion, a trademark of Du Pont Corporation for a tetrafiuorethylene resin. Teflon in a chemically inert, nonporous and nonabsorbent, relatively hard and generally form-retaining wax-like synthetic resin which is slightly elastic under low stress and which is capable of cold flowing under greater stress, and which is capable of sliding over a surface in the .manner of self-lubricating relationship therewith. The process for manufacturing the heated roller 1 includes machining a copper cylinder 10 to the proper dimensions. Right and left fuser roll caps 11 and 1'2 are cast, machined to the required dimensions, and then silver brazed to the copper cylinder. After a finish machining, the cylinder is then blasted to produce a suitable matte finish, and then air blasted to remove excess dust and grit. The cylinder thus formed is then masked in the areas of the roll that are not to be coated using a strippable vinyl or a peelable wax. The masked cylinder is suitably prepared, for example, by cleaning with a phosphate-free cleanser, and then plated, 27, thereafter cleaned as rubbing with an inhibited chlorinated solvent. The roll is then preheated and allowed to air cool at room temperature. A coating of Teflon TFE primer 28 is then sprayed onto the roll to completely cover the substrate and allowed to air dry. The primed roll is then heated to a suitable temperature to allow the primer coat 28 to fuse upon the roll and subsequently allowed to air cool to room temperature. A coating of Teon TFE enamel 9 is then spray coated upon the primed roll and allowed to air dry. The Tefion enamel coated roll is heated to a suitable temperature for a sufficient length of time to fuse the coating and then allowed to air cool at room temperature. The Tefion covered roll is then polished to the desired surface finish and cleaned with an inhibited chlorinated solvent.

A specific method well adapted for making rolls in accordance with the invention will now be described.

An electrolitic, tough pitch copper roller tube is machined to approximately 21/2 inches in diameter. Rightand left-hand fuser roller caps, cast from stainless steel, are machined to the proper dimensions and silver brazed to the copper roller tube. The brazed assemblage is then finish machined to the proper dimensions, sand plasted lightly using a -100 grit aluminum oxide abrasive to produce a matte finish of RMS, :L20 RMS, then blasted with a dust and oil-free air to remove excess dust and grit. The cylinder is masked in preparation for platingin the areas of the roll that are not to be plated using a strippable vinyl or a peelable wax. The masked cylinder is then cleaned with a suitable phosphate-free cleaning agent and nickel plated to a thickness of 0.0002 inch i0.0001 inch, and thereafter cleaned as by rubbing with a clean, lint-free rag soaked in an inhibited chlorinated solvent or xylene (dimethylbenzene). The plating mask is then removed and the roll preheated to 690 F.il F., held at this temperature for a minimum of 5 minutes and preferably 20 minutes, and allowed to air cool at room temperature. A coating of Du Pont Teflon TFE primer 850-201 or 850-204 (primer y5550-201 being preferred) is then sprayed onto the roll to a thickness of approximately 0.0003 inch to completely cover the substrate and then allowed to air dry. The primed roll is then heated to 700 F.il0 F., and held for a predetermined time at that temperature. To determine the time required for the fusing cycle, a sample roll is coated with Du Pont 852-201 indicating enamel which changes color from a milk white, when air dry, to a clear coating at the fusing temperature. The sample roll is then placed in a furnace heated to 700 F.il0 F. With enough other rolls to simulate the thermal mass of the actual furnace load during fusing. The time required for the indicating enamel to change color is recorded, and the fusing cycle of the actual rolls is taken to be this time plus minutes. After fusing, the roll is allowed to air cool to room temperature. A coating of Du Pont Tellon TFE enamel 851-224 is then spray coated upon the primed rolls. Two or more equal enamel coats should be used to coat the rolls to a thickness of .0030i.0005 inch including primer coat thickness, allowing the enamel to air dry between coats. The Teflon enamel coated roll is then air dried. The Teflon enamel coated roll is heated to 750 F., i10 F., and held for a period of time (10 minutes longer than the fusing time used for the primer coat) to fuse the Teflon coating and then allowed to air cool to room temperature. The steps of spraying the Teflon TFE enamel coating and heating to fuse this coating are repeated until the required coating thickness (.0030i-0005 inch) is achieved. The Teflon covered roll is then polished to a surface finish of RMS or better and the roll surface is then cleaned with a nonabrasive lint-free rag soaked in an inhibited chlorinated solvent or xylene (dimethylbenzene) Due to the novel process of applicants suitable means for testing the Teflon TFE substrate was devised.

The following test procedure is used to evaluate the bond and quality of the fused coat.

A small surface area of the Teflon TFE coating on a sample roll is etched by dipping the roll in sodium naphthalene for a minimum of two minutes. 'The roll is then rinsed with water, and the etched surface degreased with an inhibited chlorinated solvent. Using a sharp instrument, a 1A; inch square grid pattern (9 squares minimum) is scribed through the surface of the etched Teflon. A thin film of Eastman EK 9110 adhesive, manufactured by the Eastman Kodak Company, Rochester, N.Y., is

invention, a bond to the applied on the etched and scribed surface by applying one drop of adhesive per square inch of area..Care must be taken not to brush or roll the adhesive onto the bonding surface as even slight pressure on the adhesive film prior to mating of the bonding surfaces may initiate premature polymerization and thereby produce weak bonds. A strip of degreased, moisture-free triacetate film or its equivalent is then placed on the adhesive, pressed lirmly and allowed to dry for 1 minute minimum. The pressure is removed and the adhesive allowed to cure for a minimum of 2 minutes. The acetate strip is then pulled off of the Teflon coating. If the Teflon coating is stripped from the roll, the bond strength is inadequate and is a cause for rejection; if the removal of the acetate strip pulls the etched surface off the Teflon coating, the roll is acceptable. However, if the test procedure does not result in stripping of the etched surface oil the Teon coating, the test must be rerun.

What is claimed is:

1. A heated roller for use in cooperation with another roller in a device for fusing thermoplastic resin material on a support material, said heated roller including:

a rigid electrolytic copper tube,

said tube having a nickel plating thereon,

stainless steel closure means secured to the ends of said tube and having axially aligned openings therein,

a quartz lamp heating element concentrically aligned in said openings and supported independently thereof, means to energize said heating element, and

an outer covering of tetrailuoroethylene resin secured to said tube whereby offsetting of thermoplastic resin material is prevented.

2. In a device for fusing thermoplastic resin material on a support material wherein said support material is fed between a heated roller and a pressure roller with the resin material contacting the surface of the heated roller, the heated roller including:

a rigid electrolytic copper tube having a nickel plating thereon, and

an outer covering of tetrailuoroethylene resin secured to said tube for preventing thermoplastic resin olfsetting.

References Cited UNITED STATES PATENTS 2,802,897 8/1957 Hurd et al.

3,132,047 5/-1964- Van Dorn.

3,136,680 6/1964 Hochberg 117-75 X 3,146,490 9/1964 Cooney 107-12 X 3,168,760 2/1965 Olcott 29-132 X 3,189,729 i6/ 1965 Lusebrink 219-469 3,324,280 6/1967 Cheney et al. 117-75 X BILLY J. WILHITE, Primary Examiner.

U.S. Cl. X.R. 2,9-130, 132; 117-75; 263-6 Dedication 3,437,032.Ary'an T. Manghirmalan, Pittsford, Andrew F. Trabold, Fairport, and

Robert H. Figler, Webster, N.Y. HEATED FUSER ROLL. Patent dated Apr. 8, 1969. Dedication led Jan. 19, 1983, by the assignee, Xerox Corp. Hereby dedicates to the Public the entire remaining term of said patent.

[Official Gazette December 25. 1984.] 

